I really don't think Countdown is very good. Yeah the first hit that comes in gets reduced down to 1 damage, but then you're stressed and the second shot just wipes you out.
Getting play time with him will tell, but after throwing Hull Upgrade on him:
a) if Countdown is acting like Biggs then he's doing his job;
b) there are ways to remove stress, but you're right - focus fire will ruin him. If you're all-in on it, then have Palp in the Shuttle with Yorr behind the controls; and
c) Countdown is not just a Biggs in a Striker. He's also a feeder for Swarm Leader or Vessery because he doesn't need his action unless he's arc-dodging. I'm sure he can feed more things, like General Hux or some of the new stuff I haven't memorized yet..
If he had an EPT he'd be broken but I would sure love to throw VI on him because then he'd take even less shots. I don't think he'll be in tier-1 lists but he's easily tier-2.